Core bit



May 2, 1950 N- Ross 2,506,337

- CORE BIT Filed Oct. L20. 1948 A 2 Sheets-Sheet a I INVENTOR.

Patented May 2, 1950 CORE BIT Frederick N. Ross, Detroit, Mich, assignor to Koebel Diamond Tool 00., Detroit, Mich, a corporation of Michigan Application October 20, 1948, Serial No. '5,519' 1'- 2 Claims. (01. 2 55 22) This invention relates to drill bits or similar tools useful, for example, in drilling into hard earth strata, such as packed or consolidated sand, rock formations, sandstone and the like. The invention is especially applicable to drilling tools commonly known as core bits which are employed widely in coring operations when drilling for oil or for other purposes were it is desired, for example, to make soundings in order to obtain specimens of earth formations for geological analysis.

Core bits employed in coring wells are frequently equipped with diamonds in order to increase the drilling rate and prolong the life of the bits. In the case of diamond core bits the diamonds are usually set in a matrix formed, for example, of sintered, powdered or comminuted metal. This matrix or slug is permanently secured as by brazing to the body of the core bit which in turn is threaded for attachment to the core barrel. Since the core bits are subjected to extremely hard usage, wear and shocks during the drilling operations, the cutting portions thereof often become fractured, chipped, broken or otherwise damaged, making it usually necessary to replace the entire core bit. The damaged core bit can seldom be usefully repaired after being withdrawn from the well or hole being cored out. Hence,the bit is usually scrapped, even though only a portion thereof is damaged and the remainder is inuseful condition; The relatively high cost of the core bits, especially diamond core bits, greatly increases the cost of drilling operations as a result of the necessity of scrapping the entire core bit whenever damage thereto of such nature occurs as to render the bit inoperative or ineifectual for efficient coring work.

One of the chief objects of the invention is to overcome the foregoing disadvantages by providing a bit which is not only efficient in carrying out the work required of it but which may be readily repaired or renewed as to usefulness when only partially damaged or worn.

Another important object of the present invention is to provide a drill bit of improved construction .having cutting portions or members which may be removed and replaced, thereby prolonging the life of the bit as a whole, reducing greatly theoverall cost thereof, and as a consequence reducing the cost of drilling operations. A further object of the invention is to provide an improved drill orcore v bit comprising a. sup porting body carrying a number of drill inserts orsections which are adapted to be rigidly 2 secured in position on the body against ment or displacement while at the same time capable of being readily removed for replacement DUI-DOSES when damaged O1 Worn.

A further object of the invention is to provide a core bit having drill inserts or members which. are capable of radial adjustment in order to compensate for wear or for any other purpose, such inserts or members being preferably secured to the body by wedge means which together with the drill members are-detachable from the core bit body to permit replacement.

Another and more specific object of the inven tion is to provide acore bit comprising an annular body having radial slots or recesses for the reception of drill inserts and means for firmly and rigidly wedging the inserts in position against dislodgement during operation, said drill inserts and wedgin'g means being preferably removable and replaceable in order to prolong the life of the core bit.

A further object is to provide a core bit assembly in which the drill members are insertable into slots in the end of the tubular core bit body and held therein against axial displacement by means of taper pins driven into paired grooves in the adjacent side walls of the drill members and of the radial slots in the core bit body.

Still another object is to provide a drill construction of the character described, which is of. simplified, construction and design, thereby achieving optimum economy in manufacture and maintenance and permitting repairs and replacement of parts with a minimum of expense and.

lost time.

Other objects of this invention will appear in the following description and appended claims,

reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. 1 is a vfragmentary side elevation of a core bit embodying the present invention and installed on the lower end of a core barrel, av number of the cutters and wedging devices being removed and the core barrel and a portion of the core bit being shown in vertical mid-section to illustrate the structure clearly.

Fig. 2 .is a fragmentary enlarged bottom View of the core bit, taken in the direction of the arrows substantially along the line 22 of Fig. 1.

Fig. 3 is a fragmentary enlargedelevation of the lower portion of the core bit assembly, showing one of the cutters or drill inserts -secured.-

dislodge- Fig. 6 is a side elevation of one of the cutters or drill inserts shown in the preceding figures.

Fig. '7 is an end elevation of the drill insert shown in Fig. 6.

Fig. 8 is a bottom view of the drill insert shown in Figs. 6 and '7.

Fig. 9 is an enlarged elevation of one of the adjusting studs shown in Figs. 4 and 5.

Fig. 10 is a side elevation taken from the tapered flat side of one of the dowel wedges employed in the embodiment of the present invention shown.

Fig. 11 is a plan view of the dowel wedge shown in Fig. 10, the extent of the taper being exaggerated for the purpose of illustration and being indicated by the outline in phantom of the dimensions of the dowel before formation of the flat tapered side thereof.

-'Fig. 12 is an isometric view of the dowel wedge shown in Figs. 10 and 11, taken from the large end and the flat side thereof.

"Before explaining the present invention in detail it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in th accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

A preferred embodiment of the present invention is illustrated by way of example in the drawings in application with a core bit, preferably of the diamond type, wherein the cutting or drill elements are mounted around the lower end of an annular or tubular supporting body which in turn is mounted upon the lower end of the usual core barrel. During a drilling operation, the core barrel and bit are rotated about the longitudinal axis thereof at a suitable speed, such as between 100 R. P. M. and 150 R. P. M. The core bit cuts a generally circular hole and at the same time separates from the earth a central core which is forced upwardly through the bit and barrel as the drilling operation proceeds.

It is important that the core bit be made rugged and strong so as to enable the bit to cut the maximum possible depth before replacement becomes necessary due to wear, and further that the construction of the bit be such as to ensur the formation of an unbroken core. Heretofore, it has been the practice to secure the core bit cutting elements permanently and solidly to the body of the bit, as by brazing, thereby to assure the construction of a bit having the greatest possible strength. As pointed out above, such'a construction precludes repair of the bit in a great" many instances where damage to the bit has been only of a partial nature. In accordance with the present invention the drill or cutting elements of the bit are separable from the body, yet means are provided of such character asto enable the cutting elements to be so rigidly wedged or frictionally clamped to the body as to render the structure in effect substantially a solid unit having as high a degree of strength and ruggedness as heretofore.

Referring to the drawings, a core bit having an annular body is exteriorly threaded at its reduced upper end 22 and adapted for threading into the lower tapped end of a conventional core barrel 24. As illustrated in Fig. 1, the core bit 20 is formed with an internal tapering annular Wall 26 which converges toward the lower end of the bit 20. In accordance with usual practice there is mounted during use within the core bit 20 a tapered split ring known as a core catcher (not shown) which is provided with a number of internalribs or dogs adapted to grab th core when the split ring is forced downwardly within the tapered interior wall 28. It will be understood that during the coring operation the core slides freely through the core catcher ring, but when the bit 28 is pulled off bottom, or drawn upwardly, the core catcher is forced down into the tapered wall 26 causing the aforesaid ribs or dogs to tighten around the core.

The body of the core bit 20 terminates below the tapered inner wall 26 in an annular opening having a number of radially extending slots 28 machined in the lower edge thereof for the reception of a corresponding number of drill inserts or cutting elements 30. Each insert 30 may be formed from a matrix of sintered, powdered or comminuted metal alloy having a number of protruding diamonds 3! set in the outer surface thereof in accordance with conventional practice.

Each drill insert 30 is formed in the present instance with a plane upper surface 32 chamfered at the inner edge 34 and outer edge 36 and adapted for solidly abutting the flat base 38 of the slot 28 into which it is secured. The broad sides 40 of the insert 30' are parallel and adapted to fit snugly between the parallel axially ex tending sides of the slot 28 therefor. Extending generally radially or lengthwise of each broad side 40 is a dowel receiving recess or locking groove 42 having a plane inclined or wedge surface 42a sloping into the body of the insert 30 in both an axial downward direction toward the outer end thereof and a radial inward direction, Fig. '7. Each locking groove 42 thus has its side wall 42a-tapered in two directions. The cutting edge portions 4% of the inserts 30 extend generally parallel anad axially at their upper portions,

Fig. 6, and merge radially downward into a generally arcuate shape. The upper surface 32 is machined transversely to the radial slots 28 to provide a central rectangular sided slot or keyway 46.

As illustrated particularly in Figs. 4 and 5, the body of the core bit 20 is drilled vertically through the base 38 of each radial slot 28 to provide a cylindrical hole 48 for the reception of the shank of a dowel pin or adjusting stud 50 having a slip fit within the hole 48. The pin or stud 50 terminates in an asymmetric hexagonal head 52 having an even number of parallel axially extendlar sided upper head portion 32 adapted to fit snuglyinto any one of the radial slots 28 and has a transverse keyway or slot 46 within its upper surface 32 in which the hexagonal head'52 of the The several dr-ill' inserts '38 are rigidly held in position on the lower end-of the=corebit body 28' by means of a correspondingnumber of pairs of dowel wedges or tapered locking'pins56, each comprising an essentiallycyiindrical radially extendingbodyhaving a flat tapered side=58 adapted-"to lie 7 in' abutting relationship to the inclined inwardly tapering wall Hoof-anyone of the re-=- cesses 42.- Referring particularly to Figs; 10 through 12, it will be seen'thai. the'fiat surface 58 ofeach dowel orpin 55 tapers longitudinally and in a direction radially inward when the 'pinis driven into locking position, Fig. 2.

Opposedside walls of each insert receiving slot 28 are formed with arcuate locking grooves 58 corresponding irr curvature to the cylindrical portions of the dowels or locking pins 56. Each groove 68 is uniform in depth and extends. es sentially radiallythe full width of the slot 28, and the principal axes of each pair of grooves within each slot 28 extend in parallel relation. Upon inserting each cutting element 38=into a slot ZB thelOcki-ng grooves 42 in opposite sides of the element will register with the locking'grooves- "Lin. the side walls of the slot= The small ends of two tapered pins 55 areth'err inserted from the outside of the core bit body into the registering pairs of grooves 42, 68 and then driven inwardly in a radial direction. Since the lengthwise taper 58 of each locking pin corresponds to the radial taper of the wall 42a the pins will become tightly wedged within the grooves and will positively lock the cutting element or drill insert in place against displacement in an axial direction. As the locking pins are driven into place the coaction of the tapered surfaces 58 of the pins with the inclined walls 42a will positively force the drill insert upwardly, as viewed in Fig. 5, toward the bottom 38 of the slot 28 in the core bit body. In other words, the locking pins will by a wedging action, when driven into place, cause the drill insert to bottom within the slot 28, i. e. seat against the bottom 38 of the slot. Moreover, these pins will tightly wedge themselves between the side walls of the drill insert and the opposed side walls of the slot 28 thereby tightly anchoring the insert within the slot and in effect clamping it to the core bit body against displacement in an axial direction.

It will be noted that the lower ends of the drill inserts 38, Figs. 1 and 3, protrude somewhat below the lower rounded marginal edges of the radial slots 28, which are rounded radially at the lower edge of the core bit body similarly to the lower portions of the cutting faces 44. By relieving the intermediate portions of the core bit body 28 at 62 between the slots 28, water courses of suitable depth are provided between adjacent drill inserts 38. Thus water or other liquid pumped down through the core barrel 24 and core bit 28 may flow outwardly through the water courses 62.

As illustrated in Figs. 4, 5 and 9, the anchor pins 58 are preferably constructed so as to permit the drill inserts 38 to be adjusted radially to compensate for wear occurring during the drilling operation. In some instances-the wear takes place unevenly on some or allof the drill inserts 38 around the outside or inside, of the core bit 28. Where the drill inserts are studded on their cutthe latter to be adjusted radially either inwardly or outwardly. v

The foregoing is accomplished by forming the hexagonal head 52 either asymmetrically orescentrically with respect to the axis of the shaft of the stud 58, enabling the" stud 58 to be turned to any one of six indexed positions so as to dispose" the insert 38 in its desired radial position with respect to the core bit body 28. Adjustment of each drillinsert 38 maybe accomplished by'driv -..in --outwardly the dowel wedges 56' on opposite sides of the insert 30 to remove the same; The inserts 38 are then. removed to permitv the stud or dowel 58 to be turned to the desired positic'riiof adjustment, after which the parts areassem- .ibled-in the manner above described.

Referring to Figs. 4', 5- and 9, the eccentricityof'the asymmetric head 52 with respect to the axis of the shaft of the stud 58 is exaggeratedfoi'" the sake of illustration. It is to be understood;-

-.however,'tl'1at opposite edges of the head 52 are the keyway 46 over the head 52.

From the foregoing it will be seen that the drill inserts 38 may be adjusted radially either outwardly or inwardly in order to compensate for wear. For example, assuming that the outer surfaces of the inserts have been worn approximately .02 of an inch and the inner surfaces have been worn approximately .01 of an inch, alternate drill inserts may be adjusted outwardly .02 of an inch each and the other alternate drill inserts may be adjusted inwardly .01 of an inch each. This will enable the core bit to continue to cut the same size slot, since alternate drill inserts 38 will cut on the outside and the remaining drill inserts will cut on the inside. It will be apparent that other suitable adjustments may be made to compensate for wear on individual drill inserts, thus prolonging the useful life of the core bit. Likewise, polygonal heads similar to the head 52 but having more or less than six sides and various degrees of eccentricity or asymmetry will be employed Where required to effect the desired degrees of adjustment of the inserts 38.

With the drill inserts 38 rigidly clamped in the assembled position by means of the dowel wedges 58, it will be seen that each drill insert 38 will be held in fixed position against any possibility of displacement in any direction. Engagement between the juxtaposed sidewalls 48 of the drill inserts 38 and the sidewalls of the slots 28 will substantially key the inserts 38 against circumferential displacement. Any play of the inserts 38 Within the slots 28 Will be eliminated by the wedging action of the tapered pin 56. v 7

Similarly, engagement between the tapered flat surfaces 58 of the dowel wedges 55 and the slopingsidewalls 42a of the grooves 42 wedges the inserts 30 securely upward against the bases 38 oigthe slots 28, thereby preventing axially downward-displacement of the inserts 30.

Also, in the embodiment shown, the opposed parallel-edges of the polygonal head 52 fit snugly within the slot 46 therefor and prevent radial displacement of the insert 30. It is apparent, however, that other means for keying the inserts 30 against movement in either radial direction may be employed in conjunction with the looking or clamping pins 56.

1 Iclaim:

1.- A core bit having a tubular body provided With-a plurality of annularly spaced radial slots in one end thereof, a plurality of drill members removably mountable Within said slots, a pair of cooperating radially extending pin receiving grooves for each member, one groove of each pair being in the sidewall of the member and having a plane surface sloping into the member axially toward the outer end of the member, the second groove of each pair being in the juxtaposed sidewall of the slot for the member, and a pin adapted to be removably wedged into each cooperating pair of grooves for securing said members against axial displacement within said slots and having a longitudinally extending fiat surface adapted to lie flush with said plane sloping surface.

'2 .-A core bit having a tubular body provided,

with a plurality of annularly spaced radial slots in one end of said body, a plurality of drill memmembers against axial displacement within said slots, each pin being tapered radially and having a longitudinally extending flat surface adaptedengage said plane surface, and said plane sur-- face having a radial taper corresponding substan'- tiallyto the taper of said pin. I

FREDERICK N. ROSSJ REFERENCES CITED I The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 52,148 Dow Jan. 23, 1866 914,966 Mayer et a1. Mar. 9, 1909 1,542,172 Reed et a1 June 16, 1925 1,859,660 Erlandson May 24, 1932 2,326,908 Williams Aug. 17, 1943 

